sound on my lap doesn't work

@marwan55473 you are not telling us what it finds in the device setting, or that it finds your proper audio device. If som try to uninstall that and then reinstall either in the device settings or by a restart. The best way to do it is by going to this site and download the ISO image (you do know how to get files from an image file, if not that might be something you need to Google for as well :-) for the recovery disks. Disk 2 is the one that has all the drivers.

Of course, you can also try any of the sites that pop up when you do a Google search for "Acer Ferrari 4000 drivers" Reinstall the driver and let us know what happens. Let us know what version Windows you are trying to run on this Acer.